Merge branch 'string-optimize' into test

Author: Noam Preil

arrow/ipc/metadata.go

@@ -35,10 +35,6 @@ import (
 // Magic string identifying an Apache Arrow file.
 var Magic = []byte("ARROW1")
 
-func tostr(b []byte) string {
-	return unsafe.String(&b[0], len(b))
-}
-
 const (
 	currentMetadataVersion = MetadataV5
 	minMetadataVersion     = MetadataV4
@@ -188,7 +184,8 @@ func fieldFromFB(field *flatbuf.Field, pos dictutils.FieldPos, memo *dictutils.M
 		o   arrow.Field
 	)
 
-	o.Name = tostr(field.Name())
+	name := field.Name()
+	o.Name = unsafe.String(&name[0], len(name))
 	o.Nullable = field.Nullable()
 	o.Metadata, err = metadataFromFB(field)
 	if err != nil {
@@ -991,8 +988,9 @@ func timeFromFB(data flatbuf.Time) (arrow.DataType, error) {
 
 func timestampFromFB(data flatbuf.Timestamp) (arrow.DataType, error) {
 	unit := unitFromFB(data.Unit())
-	tz := tostr(data.Timezone())
-	return &arrow.TimestampType{Unit: unit, TimeZone: tz}, nil
+	tz := data.Timezone()
+	tzs := unsafe.String(&tz[0], len(tz))
+	return &arrow.TimestampType{Unit: unit, TimeZone: tzs}, nil
 }
 
 func dateFromFB(data flatbuf.Date) (arrow.DataType, error) {
@@ -1047,8 +1045,8 @@ func metadataFromFB(md customMetadataer) (arrow.Metadata, error) {
 		if !md.CustomMetadata(&kv, i) {
 			return arrow.Metadata{}, fmt.Errorf("arrow/ipc: could not read key-value %d from flatbuffer", i)
 		}
-		keys[i] = tostr(kv.Key())
-		vals[i] = tostr(kv.Value())
+		keys[i] = string(kv.Key())
+		vals[i] = string(kv.Value())
 	}
 
 	return arrow.NewMetadata(keys, vals), nil